The present invention concerns electric connectors which enable electrical connections to be made and broken under water. The invention applies, more particularly, to electric connections transmitting high voltages, for example in the megawatt range. An electric connection of this type is found most notably in plans for underwater hydrocarbon transfer facilities which connect a motor-driven pump to an electrical energy mains transformer.
In published British Patent Application No. 2 138 223, a connector is proposed in which two carrier elements, one having male contact pieces and the other, female contact pieces, are connected one to the other by means of a watertight, threaded device; an electric control allows the male contact pieces to be moved on their carrier element in such a way that they are brought into contact with the female contact pieces of the other element. Electric connection and disconnection are thus made possible in a watertight compartment sheltered from the environment. However, the two elements carrying the contact pieces may not be separated one from the other under water, without risk of water entering the connector after its reassembly.
U.S. Pat. No. 3,461,479 describes a connector comprised of a female element equipped with a central cavity generally cylindrical in shape. This cavity is bordered laterally by contact pieces and by a male element comprised of a pin carrying lateral contact pieces; this element is designed to fit in a watertight manner into the cavity and to expel water that has previously entered the assembly. It is practically impossible to avoid water in the connector after reassembly.
Attempts have been made to remedy these difficulties by providing, in the cavity of the female element of such a connector, a sealing piston set in a resting position which fills the cavity opening and blocks that opening; this piston may be drawn back into the cavity as a result of the thrust of the pin, thus enabling the pin to enter the cavity. This arrangement is described in U.S. Pat. Nos. 3,729,699 and 3,845,450, as well as in French Patent No. 2,529,396. In addition, this system is perfected in U.S. Pat. No. 4,188,084, which provides for directing a stream of oil under pressure between the ends of the pin and the sealing piston plunger at the instant when these ends are about to come into contact with each other, in order to avoid the entry of foreign bodies into the female element.
These devices exhibit, however, serious disadvantages. The pin, while maintaining watertightness, must slide along its entire path upon existing the male element and entering the female element; this arrangement is difficult to achieve and to keep serviceable. The sealing piston and the flexible device which draws it into a resting position must function without failure over the serviceable life of the female element. Since this element normally remains stationary, a very long life is usually expected.